Metal coating composition and method of coating titanium therewith



METAL COATING COMPOSITION AND METHOD OF COATING TITANIUM THEREWITH George F. Otto, Oreland, Pa., assignor to American Chemical Paint Company, Ambler, Pa., a corporation of Delaware No Drawing. Application October 29, 1954, Serial No. 465,721

7 19 Claims. (Cl. 117-134 This invention relates to the art of metal coating and is particularly concerned with the provision of a method and a material for coating titanium or alloys thereof in which titanium is the principal ingredient. In the following specification and claims, wherever the Word titanium appears it is to be understood as including its alloys.

As is well known, titanium is a metal which is difficult to work with. It is not readily attacked by most acids and alkalies and has a severe tendency to galling when in frictional contact with other metal surfaces or when subjected to mechanical cold-working operations.

My invention has for its principal object the provision of a method as well as of a material for producing a useful coating on titanium particularly with respect to lessening its galling tendencies.

The present invention is based upon the discovery that a useful coating may be produced upon titanium by subjecting the metal to the action of a substantially homogeneous dispersion or solution, the essential and principal ingredients of which are as follows: from 0.1% to 2.0% of acid from the class consisting of hydrofluoric, hydrofluosilicic and fluoboric acids and from 0.3% to 30% of an organiclubricant which is substantially resistant to the action of said acids. The remainder constitutes the vehicle for the principal ingredients and, where the formulation is substantially consolute, this vehicle should consist primarily of a. solvent system which is resistant to the attack of the acids mentioned and also capable of rendering the acid and the lubricantsubstantially consolute. If the formulation is in the form of a dispersion, the vehicle is waterwhich should contain sufiicient emulsifying or thickening agent, substantially resistant to the action of the acids, to emulsify and hold in homogeneous admixture the acids and the lubricant. The percentages given above are weight/volume percentages, i. e. grams per 100 ml. 1

With respect to the percentages of acid and of organic lubricant mentioned above I wish to point out that, while good results are obtainable within the limits set forth, I have found that optimum results are generally obtained where the acid content ranges between 0.5 and 1.5% and the lubricant content between 8 and 12%.

Among the organic lubricants which are useful in my invention may be mentioned paraflin wax, chlorinated parafiin wax, saturated straight chain fatty acids, (preferably those having a chain length of at least 12 because of their greater lubricity), glycerides of such straight chain fatty acids, etc.

Typical examples of the saturated straight chain fatty acids which are particularly useful with my invention are stearic acid, lauric acid and myristic acid. Typical examples of the paraflines are petroleum paraflines, whether or not chlorinated. Specifically, the high melting point paraflines are preferred especially where the coated metal is afterwards dried with the application of heat.

Where homogeneity is secured through solution the solvent system should be substantially non-aqueous and typical examples of suitable blending solvents which are useful in rendering the composition consolute are methyl isobutyl carbinol, butyl Cellosolve, butyl Carbitol, hexyl atet solvent, high flash naphtha from both petroleum and coal tarorigin, hydrogenated petroleum solvent, etc.; and

pine oil. The main requirement of the solvents is that they be substantially resistant to the attackv of the fluo-.

tine-bearing acids.

In the case of certain alloys of titanium such as RC 130B, the production of a coating is rather difficult and for this reason I prefer to include in the composition from 0.5% to 2% of phosphoric acid. It is to. be

understood, however, that in the coating of titanium itself as well as of some of its alloys the presence of phosphoric acid is not essential although its, inclusion usually produces a better result. The chief advantage of including the phosphoric acid is that the coating can be produced in much less time. Additionally, the coatings produced by such composition have shown exceptionally good lubricant properties when the coated pieces are tested on the Faville Le Vally Falex Lubricant Testing Machine.

By way of exemplification only and not necessarily by way of limitation, I wish to list the following as typical examples of homogeneous compositions which have been found to be especially useful in connection with my invention:

Example I Stearic acid gm 10 Mineral spirit m 56 Butyl Cellosolve ml 16 Pine oil ml 16 Hydrofluoric acid, 50% ml 1 Example 2 Paraffin wax g 2 Mineral spirit ml 44 Butyl Cellosolve ml 24 Pine oil m 24 Fluoboric acid, 50% ml .4

Example 3 Stearic acid gm n-Butyl alcohol ml 47 Butyl Cellosolve m .45 Hydrofluosilicic acid, 30% ml 2 Example 4 l Oleic acid gm 10 Mineral spirit ml 52 Tertiary butyl alcohol ml 35 Hydrofluoric acid, 50% ml 1 Example 5 Stearic acid gm- 10 Mineral spirit ml 56 Butyl Cellosolve ..ml 15 Pine oil ml 15 Hydrofluoric acid, 50% ml 1 (5%) Phosphoric acid, ml 1 (.85

Example 6 Flexrock Paste (50%) gm 4 Stearic acid ....gm 1 Xylol ml 20 Mineral spirit ml 40 Butyl Cellosolve m 16 Pine oil .ml.. 16 Hydrofluoric acid, 50% Soln. ml 1 Phosphoric acid, 85% rnl 1 An alloy composed of 4% manganese, 4% aluminum and 92% titanium. I

A high temperature stable chlorinated paraflln Wax.

amass? Example? Flexrock paste (so% --gm..- 4' Stearic acid gm 1 Xylol "u. ml; 20' Mineral spirit; ..ml 38 ButyluGellosolve; flu. ml- 16 Pine oil ml" 161 Hydrofluoric acid, 5il%-Soln mil... 4 Phosphoric acid, 85% ..ml. 1

7 Exampla8 Myristic acid ..gm'- 0L5 Bi'ijf' 35F (polyoxyethylene lauryl alcohol" in which the ethylenes oxide chain length is 12 gm- 0.5 water"; 'm1l Hydfoflhorio acid-(50% )L ml 110 I Example 9 7 Aluminum stear 7 gm 0E5 Stearic' acid; g;n 015' Water' ml 97' Methocel (high'yiscosity methyl cellulose) gm' 120. Fluoboric acid (50%) ml 10 Example 1.0.

Stearic acid; g;n 510 Bi'ij 3'5 (polyoxyethylene lauryl' alcohol in which...

the ethylene oxide chain length is 12) gm 2.0 Brij 30 ((polyoxyethylene, lauryl alcohol having a chain length of 4) gm 1.0 Water: ml 89 Hydrofiuorie acid (-50%) ..rn'l 2 v Examplell Oleic-aeid:. ..-gm 26.8 Mineral spirits ml 39 Butyl Cellosolve ml 15 Pine' oil- 7 ml 15 Hydrofl'uoric'acid; ml; 1

In the preceding examples the" total; volume of each" is approxiirratelydotlrnl; Examples 1 to Tinclusive and 11 form substantially non-aqueous solutions and Examples 8 to 10 form dispersions.

Irrorder to: carry outthe process ofthe presentinvenr tion it is preferable that-the titanium shouldj lie-reason: alily'cl'ean: The cleaning step, .per se, formsno part of the presentinvention and may be performedin any 1 desired manner as by -solvent-n'cleaning, alkali cleaning or acid cleaning, after which the cleaned parts arctreated with asolution according to the present inventionhy, ime mersi'ng, spraying or otherwise applying thesolutionto the surface and"permitting it to.remain.thereon..or. to be repeatedly appli'edthereto for a length of time which is sufficient to produce av visible coating. After the visible coating has been. obtained, if the treatment hasbeemby means oflitnmersion or spray processes, the-.objeetshould be removed from contact with the treating.,solut-ion..and dried. Iffdesi'ted, this diying may he done withthe. ap; plication .of heat but if'so care shculdlbetakenso. that theheat cmployedis not high enough to causefihelubri cant'to melt'and"run from the surface of the work. In this connection also itzwil-l bB7GbVl0l1S that, where the coated titanium is to be employed in .a hot atmosphere su'i'tahlwhigh" melting point lubricant should. be" incor: p orated imthetreatingsolution:

Theexact" chemical 'nature of the coatings produced .by my new-process and material is'not fully known although it is'possiblv that the" coatings conversion coatings which adsorbor absorb the:- lubricant" in such a fashion that there -is-co actionbetween theconyersion coating and the lubricant-and 'that "this produces thedesirableresults characteristic of. my invention.

The present application is a continuatiominepartiof 4.. my earlier application Serial No. 408,593, filed February 5; 1954, now abandoned:

I claim: 7

1. A method of coating titanium which includes the step of treating the surfacewith an admixture consisting essentially. oftrom 0.1%. to 2.0% ofnacidtrom the.class which consists. of. hydrofluoric, hydrofluosilicic and fluoboric acids and" from 0.3% to 30% of an organic lubricant: substantially resistant; to: the: action; of:v said? acids 1 with i the remainder: constituting a. vehicle which is substantially resistant to the attack of said acids' and-capable of, rendering the. admixture, homogeneous,, th.e.:treatment with said admixture: being continued until a visible coating is produced.

2. The method of'claim lwherein the organic lubricant ischosenfrom the .class whichconsists ofiparafiinwax, chlorinatedparalfin wax, saturated" straigh'tpchain, fatty, acidsv and glyceridesof such fatty acids.

3,. The method of, claim,1 whereinthe organic, lubricant. is. chosen from the" class'consisting ofthe saturated straight. chainvfatty acids havinga chain length ofat' least.12.'

4. The methodofclaiml wherein the organic lubricant is chosen from theclass which consists of stearic acid, lauric acid'and myristic acid.

5'. The methodof claim 1. wherein the treated surface is dried'at a. temperature below. that atwhich the lubricant willmelt and run .from the surface..

6'. Themethodof claim 1 wherein. the admixture in: cl'udes from 0.5% to 2% of phosphoric acid;

7. A method of coating titanium which includes the step ofl'treating the surface with an admixture consisting essentially ofjfr'om 0.1% to. 2.0% ofiacidfromthe class which consists of, hydrofluoric, hydrofluosilicic and fluolioric. acids and'from 0.3% to 30% of'an organic lubri cant chosen. from the class consisting ofiparafiinwaxj chlorinated paraflin wax, saturated straight ichain fatty acids .havinga chainlength of at.least 12'and'glycerid'es ofisuch. fatty caidstandwith theremainder constituting avehicle wherein homogeneity is secured. through useof a'solvent system which, is chosen from the. class which consists of 'methyl' isobutyl' Carbinol; butyl Cellosolve, butyl Carbitol, hexyl' Cellosolve, kerosene, Stoddardsoh vent,,high' flash naphtha, hydrogenated'petroleum solvent andtp ine oil, the treatment with said" admixture being continued until a visible coatingis produced.

8. A metal coating bath the essential coating prodilcingjngredients of'which are from 0.1% to 2% of acid from;- the class which consists of hydrofluoric, hydro: fiuosilicic and fluoboric acids and'from 013% to.30%" of an organiolubrieant substantially resistant'to the. action of said acids with the remainder constituting a vehicle which is substantially resistant to the attack ofsaid'acids and" capable. of rendering the admixture homogeneous.

9' A bath according to claim 8' whichlincludes also fromrOI5% to 2% of phosphoric'acidi 1021A bathaccording to claim 8" wherein the-lubricant is chosenfrom the classwhichconsists'of-parafiin wax, chlorinated" parafiin wax, saturated straight chain" fatty acid'srandiglycerides 'ofisuch fatty acids:

Abath'" according to claim' IO Wherein the fatty acids have a chain length of' at'leastl2';

12. A consolute metal coating bath the .essential coating producing ingredients of which are from 011% to 2%; of acid from the 'class which consists of hydrofli'loric, hydrofi'uosilicidand fluoboric acids and'from 0.3% to 30% of anorganic:lubricantsubstantially resistant to, the action of 'said acids with the remainder, constituting a solvent system: which also, is substantially resistant to theattack of said acids andcapableof rendering the, acid andjthe lubricant substantially consolute.

13. Abathaccordingtoclaim.IZQWhereintlie;lubricant is;chosen, fromthe .class. whihconsists .ofQparaflihwax, chlorinated'parafiin: wax, saturated. straight. chain. fatty acids and 'glycerides. oflsuch; fatty acids .-and;lwhereiir.the

5 solvent system is chosen from the class which consists of methyl isobutyl Carbinol, butyl Cellosolve, butyl Carbitol, hexyl Cellosolve, kerosene, Stoddard solvent, high flash naphtha, hydrogenated petroleum solvent and pine oil.

14. A bath according to claim 13 wherein the fatty acids have a chain length of at least l2.

15. A bath according to claim 13 which includes also from 0.5% to 2% of phosphoric acid.

16. A bath according to claim 12 which includes also from 0.5% to 2% of phosphoric acid.

17. A bath according to claim 12 wherein the organic lubricant is chosen from the class consisting of the saturated straight chain fatty acids having a chain length of at least 12.

18. A bath according to claim 8 wherein the content 15 6 between 8 and 12%.

References Cited in the file of this patent UNITED STATES PATENTS 2,487,306 Carnell Nov. 8, 1949 2,588,234 Henricks Mar. 4, 1953 2,659,252 Kipp Nov. 17, 1953 FOREIGN PATENTS 118,069 Australia Feb. 17, 1944 645,425 Great Britain Nov. 1, 1950 

12. A CONSOLUTE METAL COATING BATH THE ESSENTIALLY COATING PRODUCING INGREDIENTS OF WHICH ARE FROM 0.1% TO 2% OF ACID FROM THE CLASS WHICH CONSISTS OF HYDROFLUORIC, HYDROFLUOSILIC AND FLUOBORIC ACIDS AND FROM 0.3% TO 30% OF AN ORGANIC LUBRICANT SUBSTANTIALLY RESISTANT TO THE ACTION OF SAID ACIDS WITH THE REMAINDER CONSTITUING A SOLVENT SYSTEM WHICH ALSO IS SUBSTANTIALLY RESISTANT TO THE ATTACK OF SAID ACIDS AND CAPABLE OF RENDERING THE ACID AND THE LUBRICANT SUBSTANTIALLY CONSOLUTE. 